The JspFactory is an abstract class that defines a number of factory
methods available to a JSP page at runtime for the purposes of creating
instances of various interfaces and classes used to support the JSP
implementation.

The actions and template data in a JSP page is written using the
JspWriter object that is referenced by the implicit variable out which
is initialized automatically using methods in the PageContext object.

Package javax.servlet.jsp Description

Classes and interfaces for the Core JSP 2.1 API.

The javax.servlet.jsp package contains a number of classes and
interfaces that describe and define the contracts between a JSP page
implementation class and the runtime environment provided for an
instance of such a class by a conforming JSP container.

JSP Page Implementation Object Contract

This section describes the basic contract between a JSP Page
implementation object and its container.

The main contract is defined by the classes
JspPage
and HttpJspPage.
The JspFactory class describes the mechanism to
portably instantiate all needed runtime objects,
and JspEngineInfo provides basic information on
the current JSP container. Class JspApplicationContext
stores application-scoped information relevant to JSP containers.
It was added in JSP 2.1 to support the integration of the unified
Expression Language.

None of these classes are intended to be used
by JSP page authors; an example of how these classes may be
used is included below.

Exceptions

For JSP error pages, the ErrorData class encapsulates information
about the error.

An Implementation Example

An instance of an implementation dependent subclass of the
PageContext
abstract base class can be created by a JSP implementation class at
the beginning of it's _jspService() method via an
implementation default JspFactory.